Parental dietary effect on embryological development response to toxicants with the sea urchin Arbacia punctulata.

The role of echinoid parental nutrition in early-life stage toxicity is not well understood. Arbacia punctulata were fed either a fresh diet consisting of organic lettuce and carrots or a dry feed. Embryos from parents fed the dry feed exhibited lower sensitivity to copper, whereas the opposite occurred with 1,3,5-trinitrobenzene and sodium dodecyl sulfate (SDS). EC(50) values for the dry and fresh feed treatments, respectively, were 41.0 and 29.9 microg/L for copper, 0.5 and 1.8 mg/L for 1,3,5-trinitrobenzene, and 3.5 and 5.6 mg/L for SDS. The data suggests that nutritional standardization for sea urchins in ecotoxicological laboratories needs to be addressed and further investigated.

The influence of biomass on the toxicity of hydrophobic organic contaminants.

Hydrophobic organic contaminants (HOCs) enter the marine environment through several means, including industrial, urban, and agricultural runoff, and accumulate in sediments. Methods for measurement of sediment toxicity include porewater tests using sea urchin (Arbacia punctulata) fertilization and embryological development assessments. Previous studies investigating sediments from Boston Harbor determined that significant binding of contaminants to organic matter led to insufficient evidence of the bioavailability of HOCs in porewater toxicity tests. It was hypothesized that excessive biomass in testing systems prevents a critical body residue of HOCs from forming, thus curbing toxic effects. In this study, the effect of biomass on the toxicity of phenanthrene (a polycyclic aromatic hydrocarbon) and lindane (an organochlorine pesticide) were assessed individually and combined in a mixture. The fertilization toxicity test for phenanthrene and mixture solutions containing both compounds revealed less biomass in the test vial caused higher toxicity levels, the fact of which was enhanced with increased hydrophobicity. The 50% inhibition concentration (IC(50)) of phenanthrene to sea urchin fertilization success in test vials with 50 eggs/mL (lowest biomass concentration tested) was 3.72 micromol/L, but in vials with 100 to 400 eggs/mL, the IC(50) was >4.12 micromol/L. Toxicity of several concentrations of the phenanthrene and lindane mixture to sea urchin fertilization success and embryological development was significantly higher at lower biomasses (50 and 100 eggs or embryos/mL) than with biomasses > or =200 eggs or embryos/mL. The results suggest that when testing environmental samples that may contain HOCs, lowering the biomass can help better estimate sediment toxicity using porewater tests.

Toxicity of phenanthrene and lindane mixtures to marine invertebrates.

Surface waters near industrialized and agricultural areas are contaminated with hundreds of different pollutants from a variety of sources. Methods for measurement of sediment, surface water, and porewater toxicity in marine environments include the sea urchin (Arbacia punctulata) fertilization and embryological development tests and copepod (Schizopera knabeni) survival and hatching success assessment. The concentration addition model was applied to determine whether toxicity of two compounds, phenanthrene (polycyclic aromatic hydrocarbon) and lindane (organochlorine pesticide), when combined can be accurately assessed because of similar modes of action. Mixture analysis determined the sea urchin fertilization test to exhibit additivity (TU(mix) = 1.13), while the copepod test exhibited a synergistic effect (TU(mix) = 0.22). Mixture toxicity data for the sea urchin embryological test were not conclusive because of the lack of toxicity of the individual chemicals. The synergistic effect to copepods is a concern as it indicates that greater toxic effects may occur when the compounds are present in mixtures. Results from this research suggest that increased toxicity to some categories of organisms should be expected near agricultural and industrial areas where pesticides and other types of compounds may occur simultaneously.

Sediment toxicity tests using the burrowing amphipod Tiburonella viscana (Amphipoda: Platyischnopidae).

The present study investigated the feasibility of the use of the burrowing amphipod Tiburonella viscana for sediment toxicity assessments. The effects of reference toxicants, salinity, sediment particle size, and sediment contamination on amphipod survival were analyzed. The sensitivity of T. viscana to zinc, chromium, and sodium dodecyl sulfate (SDS) in acute tests was similar to that of other crustaceans. The 48-h LC(50) (lethal concentration to 50% of the test organisms in a 48-h exposure) values for T. viscana (95% confidence intervals in parenthesis) were 0.79 (0.56-1.12), 5.85 (4.9-7.0), and 3.41 (2.87-4.04) mg L(-1) for zinc, chromium, and SDS, respectively. The species tolerated salinity as low as 19 ppt under laboratory conditions, indicating its suitability for use in tests with some estuarine sediments. The survival of T. viscana was not affected by grain size in field-collected sediments ranging from 60.6% silt and clay to 95.5% sand, but survival was significantly reduced in laboratory-sieved sediments containing only one or two particle sizes, e.g., only medium and coarse sand, or medium sand, or fine sand, or only fines, suggesting that a mixed grain size distribution is necessary for amphipod survival.

Influence of potentially confounding factors on sea urchin porewater toxicity tests.

The influence of potentially confounding factors has been identified as a concern for interpreting sea urchin porewater toxicity test data. The results from >40 sediment-quality assessment surveys using early-life stages of the sea urchin Arbacia punctulata were compiled and examined to determine acceptable ranges of natural variables such as pH, ammonia, and dissolved organic carbon on the fertilization and embryological development endpoints. In addition, laboratory experiments were also conducted with A. punctulata and compared with information from the literature. Pore water with pH as low as 6.9 is an unlikely contributor to toxicity for the fertilization and embryological development tests with A. punctulata. Other species of sea urchin have narrower pH tolerance ranges. Ammonia is rarely a contributing factor in pore water toxicity tests using the fertilization endpoint, but the embryological development endpoint may be influenced by ammonia concentrations commonly found in porewater samples. Therefore, ammonia needs to be considered when interpreting results for the embryological development test. Humic acid does not affect sea urchin fertilization at saturation concentrations, but it could have an effect on the embryological development endpoint at near-saturation concentrations. There was no correlation between sediment total organic carbon concentrations and porewater dissolved organic carbon concentrations. Because of the potential for many varying substances to activate parthenogenesis in sea urchin eggs, it is recommended that a no-sperm control be included with every fertilization test treatment.

Toxicological and chemical assessment of ordinance compounds in marine sediments and porewaters.

Toxicological and chemical studies were performed with a silty and a sandy marine sediment spiked with 2,6-dinitrotoluene (2,6-DNT), 2,4,6-trinitrophenylmethylnitramine (tetryl), or 2,4,6-trinitrophenol (picric acid). Whole sediment toxicity was analyzed by the 10-day survival test with the amphipod Ampelisca abdita, and porewater toxicity tests assessed macro-algae (Ulva fasciata) zoospore germination and germling growth, sea urchin (Arbacia punctulata) embryological development, and polychaete (Dinophilus gyrociliatus) survival and reproduction. Whole sediments spiked with 2,6-DNT were not toxic to amphipods. The fine-grained sediment spiked with tetryl was also not acutely toxic. The tetryl and picric acid LC50 values in the sandy sediment were 3.24 and 144 mg/kg dry weight, respectively. The fine-grained sediment spiked with picric acid generated a U-shaped concentration-response curve in the amphipod test, with increased survival both in the lowest and highest concentration. Grain-size distribution and organic carbon content strongly influenced the behavior of ordnance compounds in spiked sediments. Very low concentrations were measured in some of the treatments and irreversible binding and biodegradation are suggested as the processes responsible for the low measurements. Porewater toxicity varied with its sedimentary origin and with ordnance compound. The sea urchin embryological development test tended to be the least sensitive. Tetryl was the most toxic chemical in all porewater tests, and picric acid the least toxic. Samples spiked with 2,6-DNT contained a degradation product identified as 2-methyl-3-nitroaniline (also known as 2-amino-6-nitrotoluene), and unidentified peaks, possibly degradation products, were also seen in some of the picric acid- and tetryl-spiked samples. Degradation products may have played a role in observed toxicity.

Sediment toxicity identification evaluation (TIE) studies at marine sites suspected of ordnance contamination.

A sediment quality assessment survey and subsequent toxicity identification evaluation (TIE) study was conducted at several sites in Puget Sound, Washington. The sites were previously suspected of contamination with ordnance compounds. The initial survey employed sea urchin porewater toxicity tests to locate the most toxic stations. Sediments from the most toxic stations were selected for comprehensive chemical analyses. Based on the combined information from the toxicity and chemical data, three adjacent stations in Ostrich Bay were selected for the TIE study. The results of the phase I TIE suggested that organics and metals were primarily responsible for the observed toxicity in the sea urchin fertilization test. In addition to these contaminants, ammonia was also contributing to the toxicity for the sea urchin embryological development test. The phase II TIE study isolated the majority of the toxicity in the fraction containing nonpolar organics with high log K(ow), but chemical analyses failed to identify a compound present at a concentration high enough to be responsible for the observed toxicity. The data suggest that some organic or organometallic contaminant(s) that were not included in the comprehensive suite of chemical analyses caused the observed toxicological responses.

Development of marine toxicity data for ordnance compounds.

A toxicity database for ordnance compounds was generated using eight compounds of concern and marine toxicity tests with five species from different phyla. Toxicity tests and endpoints included fertilization success and embryological development with the sea urchin Arbacia punctulata; zoospore germination, germling length, and cell number with the green macroalga Ulva fasciata; survival and reproductive success of the polychaete Dinophilus gyrociliatus; larvae hatching and survival with the redfish Sciaenops ocellatus; and survival of juveniles of the opossum shrimp Americamysis bahia (formerly Mysidopsis bahia). The studied ordnance compounds were 2,4- and 2,6-dinitrotoluene, 2,4,6-trinitrotoluene, 1,3-dinitrobenzene, 1,3,5-trinitrobenzene, 2,4,6-trinitrophenylmethylnitramine (tetryl), 2,4,6-trinitrophenol (picric acid), and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). The most sensitive toxicity test endpoints overall were the macroalga zoospore germination and the polychaete reproduction tests. The most toxic ordnance compounds overall were tetryl and 1,3,5-trinitrobenzene. These were also the most degradable compounds, often being reduced to very low or below-detection levels at the end of the test exposure. Among the dinitro- and trinitrotoluenes and benzenes, toxicity tended to increase with the level of nitrogenation. Picric acid and RDX were the least toxic chemicals tested overall.

Expanded applications of CT. Helical scanning in five common acute conditions.

Helical CT has become a valuable imaging tool for detection of pulmonary embolism, deep venous thrombosis, ureteral colic, acute small-bowel obstruction, and acute appendicitis. Generally, helical CT has good sensitivity and specificity values, and scans can be performed more quickly than previous gold standard diagnostic examinations for the conditions mentioned. In some cases, helical CT can also identify other findings that may be responsible for a patient's symptoms. One notable disadvantage of helical CT is the charge for the procedure, which in some circumstances can be considerably more costly than diagnostic examinations preferred previously. However, because helical CT can often obviate the need for other tests--and may consequently reduce hospital stays--this technology may have the ability to reduce overall expenditures. Cost of helical CT is therefore a multifaceted issue and requires further study before conclusions can be drawn.

Computed tomography and ultrasonography in the diagnosis of appendicitis: when are they indicated?

HYPOTHESIS: Relative merits and indications exist for ultrasonography (US) and computed tomography (CT) in the diagnosis of appendicitis. DESIGN: Prospective study. SETTING: General community and tertiary care hospital. METHODS: Ninety-nine patients (50 males and 49 females) were studied. Following consent, the initial disposition was recorded, designating the patient for operation, observation, or discharge from the hospital. Each patient was studied by CT and US. Studies were independently evaluated by 2 radiologists, and the results were designated as positive, negative, or equivocal. The surgeon reevaluated patients before and after learning the results of US and CT, recording whether the CT scan, US, or reexamination influenced the final disposition. RESULTS: Fifty patients had appendicitis; 6 appendixes were perforated. The initial clinical impression called for 44 operations, 49 observations, and 6 discharges. Thirty-four patients had their treatment plan changed from the initial disposition. Ultrasonography did not affect the initial impression. In contrast, 18 patients were rediagnosed solely on CT scan findings. Seven patients were rediagnosed by reexamination. Of 44 patients initially designated for operation, the CT scan and reexamination spared 6 females from surgery; the negative appendectomy rate potentially decreased from 50% to 17% (P =.03). The CT scan, US, or reexamination failed to spare 2 males from exploration with negative results. Of the 49 patients initially designated for observation, 23 were rediagnosed after reevaluation, 13 were discharged from the hospital, and 10 underwent expedient operation. One patient was spared from inappropriate discharge from the hospital. The reliability of the CT scan was good, with high sensitivities and specificities. Equivocal scan results lowered the diagnostic value. CONCLUSIONS: Selective use of a CT scan with a second examination can improve the diagnostic accuracy and management of suspected cases of appendicitis by (a) reducing the negative appendectomy rate in females, (b) moving patients from observation to earlier operation or discharge from the hospital, and (c) preventing inappropriate discharge of patients with appendicitis.

Computer-aided mammographic screening for spiculated lesions.

PURPOSE: To study the use of a computer vision method as a second reader for the detection of spiculated lesions on screening mammograms. MATERIALS AND METHODS: An algorithmic computer process for the detection of spiculated lesions on digitized screen-film mammograms was applied to 85 four-view clinical cases: 36 cases with cancer proved by means of biopsy and 49 cases with negative findings at examination and follow-up. The computer detections were printed as film with added outlines that indicated the suspected cancers. Four radiologists screened the 85 cases twice, once without and once with the computer reports as ancillary films. RESULTS: The algorithm alone achieved 100% sensitivity, with a specificity of 82%. The computer reports increased the average radiologist sensitivity by 9.7% (P = .005), moving from 80.6% to 90.3%, with no decrease in average specificity. CONCLUSION: The study demonstrated that computer analysis of mammograms can provide a substantial and statistically significant increase in radiologist screening efficacy.

Left ventricular-coronary sinus fistula after mitral valve replacement: case report and ultrafast CT findings.

Postoperative fistula from left ventricle to right atrium is a rare complication of mitral valve surgery. We describe a case identified by ultrafast computed tomography (CT) and we review the literature regarding this entity.

CT-guided needle biopsy of the pancreas: a retrospective analysis of diagnostic accuracy.

The purpose of this study was to evaluate the accuracy of percutaneous needle biopsy of the pancreas and to compare its sensitivity with that of simple computerized tomographic (CT) prediction of malignancy. The records of 41 patients who underwent CT-guided percutaneous needle biopsies of the pancreas during a 4-yr period were reviewed retrospectively. Pre-biopsy CT scans were evaluated independently by two experienced radiologists in a blinded fashion. Needle biopsy yielded a correct diagnosis of cancer (sensitivity) in only 45% of patients ultimately found to have a malignancy, whereas the radiologic interpretation alone correctly predicted cancer in 76% of such patients. The negative predictive value of needle biopsy was no better (43%) than the radiologist's CT interpretation alone. Our findings confirm previous observations that percutaneous needle biopsy is an insensitive method of diagnosing pancreatic cancer. In our experience, needle biopsy proved less accurate than expert radiologic interpretation of CT scans alone.

Stroke associated with coronary artery bypass surgery.

Medical records and neuroimaging studies of 30 patients with major neurologic events after coronary artery surgery were reviewed. Two thousand and twenty-nine coronary artery bypass graft operations were performed in our institution between October 15, 1985, and December 27, 1989. Of these, there were 30 documented neurologic events suggesting acute ischemic injury during the intraoperative or the postoperative period. Clinical manifestations included hemiparesis, monoparesis, aphasia, bilateral cortical dysfunction, cortical and brainstem dysfunction, and left homonymous hemianopsia. There were five deaths directly attributable to neurologic injury. Twenty-two patients had a CT scan of the head, of which 15 showed evidence of acute infarction, two suggested watershed lesions from cerebral hypoperfusion, and the remainder showed findings consistent with multiple cerebral emboli or primary intracranial occlusion. Five carotid arteriograms and one digital subtraction arteriogram of the carotids were obtained. Angiographic findings revealed two common carotid artery occlusions, one callosal marginal artery occlusion, and two cases of bilateral high-grade internal carotid stenoses. Our findings support the contention that in patients who suffer cerebral infarction associated with coronary artery bypass grafting, the main mechanism of injury is cerebral embolization rather than cerebral hypoperfusion.